There are at least a couple of Spyder Ryders here in Oz who regularly tow electrically braked trailers/campers that weigh in somewhere around 700kgs/1500#'s :shocked:
Not saying it's legal or that it's even advisable in the craziest of universes, but they've been doing it..... aaand apparently without incident or repurcussion for many years now! Between them they must've covered 10's if not 100's of thousands of miles towing these things!!
And there's another bloke in Western Australia who's fitted a 'Trike conversion' to his Spyder to increase its legal towing limit so he can 'legally' tow his 700 or so kg camper (he fitted one of those 'dual rear wheels with diff' trike kits.... so to you'n me it's now a quad, but apparently the Approval Engineer got it thru as a legit 'trike conversion' on a 'motorcycle'.... :dontknow: )